Simplify. Rewrite the expression in the form $5^n$. $\dfrac{5^{-5}}{5^{8}}=$
Recall that $\dfrac{x^n}{x^m}=x^{n-m}$. $\begin{aligned} \dfrac{5^{-5}}{5^{8}} &= 5^{-5-8} \\\\ &= 5^{-13} \end{aligned}$